Gauge Service FAQs

Reset battery life to 190 hours. Ensure charger is good. Check charger jack to see if it is loose/broken. Possible bad battery pack.

My gauge displays tube error. What's the problem?

Take the gauge to a clean, dry environment and remove the control panel or "scaler". Check for loose hardware inside the gauge that could short the high voltage. Check for moisture inside the gauge and, if moisture is present, remove the scaler and dry overnight with a fan.

Why does my gauge fail the standard count?

Ensure that the gauge is positioned properly. Make sure that stored standard counts are appropriate by comparing to the factory standard counts.

When I try to get my density, I get nothing but +'s. Why?

Obtain the gauge's most recent calibration printout and check that the calibration constants in the memory match those on the printout. Also, verify that the depth strip is functioning correctly. Check for correct standard counts.

Why are my gauge readings off?

Ensure you have a good standard count. Verify you are at the correct depth. Check to make sure no offsets are enabled.

Why is my gauge hard to index?

Magnalube is the recommended lubricant. Place a small amount on the source rod and exercise the rod up and down. Check the bottom of the gauge to make sure dirt has not accumulated in the sliding block or base plate area.

Why does my gauge indicate safe position when it is in backscatter mode?

You need to calibrate the depth strip. If this doesn't fix the problem, your gauge may need servicing.

What is the prescale factor for my Troxler gauge?

In order to scale the count values to a reasonable number of digits, Troxler devices use prescale factors when performing measurements, standard counts and any other diagnostics count. In other words, the count that a gauge displays is the total number of ionization events measured by the gauge divided by the appropriate prescale factor.

The prescale factor is typically not needed by the gauge operator. However, the ASTM standards D 6938 and D 2950 give a formula to check the stability of the standard counts which requires the use of the prescale factor. The prescale factors are listed below:

For Troxler Models 3401, 3411, 3430, 3430 Plus, 3440, 3440 Plus, and 4300 devices, a prescale of 16 is to be used in the formula when a 4-minute standard count is performed.

For Troxler Models 3450 and 4640 devices, a prescale of 8 is to be used in the formula when a 4-minute standard count is performed.

My gauge is locked up and there is no keypad response.

Press and hold the OFF button for 15-30 seconds until the gauge turns off. If it does not turn off, remove the scaler and unplug the ribbon cable from the baseboard. Plug the cable back in and turn the gauge on, allowing it to go through its 5 minute self-test.

Take a new standard count. (Note: A standard count must be taken each time a 3411 is turned off. It does not store standard counts.) Ensure depth switch is at the correct depth.

Gyratory Compactor Service FAQs

What could cause the voids to be high in compacted specimens on a 4140?

Possibly the brake is slipping and thereby not allowing the angle to be fully set on. Tighten the brake cable until the brake ring doesn't slip during angle on operation.

What causes the mold to get stuck in a 4141? How is the mold removed?

A zero angle screw stuck in the down position. Power off machine and remove the top electronic box. Unscrew the three zero angle screws (pulley atop each). Power on machine and escape to Idle screen. Press Setup then item 6 (manual). Select item 5 (unlatch mold). Select item 4 (lower ram).

What causes the 4141 to fail pressure calibration?

The most likely cause is a loose one inch nut on the jack. Remove the front panel and lift the jack shaft by hand (place height standard under head inside chamber to keep it held up). Remove the one inch nut atop the jack screw and turn the shaft counterclockwise to screw the anti-rotation bar firmly down. Clean the nut and apply blue Loctite to the treads before tightening it back on the jack shaft.

What causes a loud noise combined with the ram stopping on a 4140?

This is most likely caused by a failure on the CPI board. Please contact technical support for assistance.

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What causes garbled display data on the 4140 console display?

A power glitch can cause this if the printer power cord is plugged into an outlet other than the Aux outlet on the rear of the compactor. Power down both printer and compactor and plug printer power cord into compactor. Power on compactor and then printer.

A failed solid state relay (the middle one on the power cord panel). Please contact technical support for assistance.

What causes the 4155 to signal end of burn after only twenty some minutes?

The constants may have been corrupted by a power glitch. Print the constants, reset the machine and chamber, re-calibrate the Weight Window, recalibrate the scale, and re-enter the temperature constants.

What causes the 4155 temperature display to show around 1480 and the chamber to not heat?

NTO FAQ's

Why is my NTO is not heating up?

Ensure that the door latch is making good contact with the door interlock switch. Adjust the door latch if needed.

Why is my NTO smoking?

Inspect and clean the easy access side plenum of the NTO (refer to instructions in the manual). Check the exhaust system and ensure it is clean and there is nothing restricting the airflow, such as a mesh screen. Ensure that the exhaust duct is 4" in diameter and not 3" duct, which will slow the airflow considerably. Try to eliminate any 90-degree elbows in the exhaust duct that can slow the airflow considerably. Inspect and verify that the NTO fan is turning.

Why am I getting unburned material in my sample trays?

Ensure that you have evenly spread the sample in the sample trays.

Ensure the NTO is preheated properly before using. Recommended preheat temperature for 4730 (120V unit) is 400C and for 4731 (240V unit), 370C.

Verify the chamber temperature at the end of the burn. It should be below 400C. If higher, inspect and clean the NTO and the exhaust system. Change the burn profile from Default to Option 1 (less aggressive burn profile).

During the burn process the scale shows erratic readings?

Ensure that the basket assembly is centered in the furnace and not touching one of the sides.

Additional Questions? refer to the troubleshooting section of the NTO Operator's manual

Gyratory Compactor FAQS

Why are my gyratory specimens not matching specimens of another gyratory?

Check the preheat temperature of molds and hot-mix-asphalt (HMA). Make sure they have been heated up to the same specified temperature. Low mold and/or HMA temperature will cause lower compaction. Make sure the HMA is covered while preheating the mix. Uncovered mix will not compact as well.

>What kind of basic maintenance can I do to my gyratory?

Grease cam followers daily using Teflon based lubricant such as Magnalube-G (a can supplied with the gyratory). Keep gyratory clean of binder build up. Clean the ram head, and molds daily and cam followers weekly using WD-40. Remember to re-grease cam followers after cleaning.

Why are my gyratory specimens coming up at 135-140mm when they used to be 110-115mm?

Make sure you calibrate the height using mold's bottom puck under the height standard. Leaving the bottom puck out will cause a 25mm errorin the height reading.

The printer for my model 4140 is not working or is printing strange characters.

Make sure to plug the printer into the outlet on the back of the gyratory (not into a standard wall outlet) and make sure the printer's on-line light is on.

The outlet on the back of the gyratory is not working (printer is not turning on)?

Check and replace the fuse for the outlet.

General calibration problems:

Check all cable connections

Check the calibration equipment power connection

For the 4140, ensure that the height standard (for height calibration) and the load cell (for pressure calibration) are centered on the turntable

For the 4141, ensure that the height standard (for height calibration) and the load cell (for pressure calibration) are centered on the ram head and then offset approximately 1/4 inch (6mm) toward the rear of the chamber

Zero Angle System Deactivation Procedure

The following procedure describes the deactivation of the zero angle screw system in the 4141 model compactor. It has been determined that disabling this system will have no adverse affects on the operation of the 4141.

The 4141 has three (3) ZERO ANGLE screws that are threaded shafts with a pulley mounted on top. A motor with a pulley drives a rubber belt that drives the three screws down and up.

Turn off power switch and remove power cord and printer cable.

Unscrew the three bolts from the top plate of the 4141 and remove the top plate.

Unscrew the three black plastic handled bolts from the top of the electronics module (hereafter referred to as ELMO) and set them aside.

Unscrew and unplug the three (3) cable assemblies on the ELMO (one near center top and two near power switch).

Grasp the two handles atop the ELMO and lift it out of the 4141.

Look down in the area below where the ELMO was and to the left rear to locate the belt drive motor. Locate the short (2 inch) red jumper wire on this motor and unplug it. Use a knife or cutter to cut the drive belt and discard it.

Look inside the sample chamber at the ceiling to make sure all three zero angle screws are fully up. Use a wrench to loosen any that may be stuck and screw them up until they are not down any inside the chamber.

Re-install the ELMO and reconnect the three cables. Install and tighten the three plastic handled bolts.

Bolt on the top plate and reconnect power and printer cables.

Additional Questions? refer to the troubleshooting section of the Operator's manual

Nuclear Gauge and Field Equipment FAQ's

Do I need to have a target density (Proctor, Marshall, Voidless) programmed into the gauge in order for it to work?

No. The target value is only used by the gauge to calculate the percent of compaction that has been achieved. The gauge will still give Wet Density, Dry Density, Moisture and Percent Moisture results without the target density entered. The percent compaction can be calculated at a later time if necessary.
Example: (DD/Proctor) x 100 = %Proctor or (WD/Marshall) x 100 = %Marshall

>How will frost (frozen material) affect the gauge readings?

The percent moisture result will be elevated and the dry density read by the nuclear density gauge will be lower if the material contains frost. Therefore, the tests will fail. When the water freezes it expands and takes up a larger volume in the material beneath the gauge. Because water is less dense than the measured material, the density will be lower and the percent moisture will be higher. It is commonly written in engineering specifications that "no fill may be placed over frozen material." In extreme cases, settling could occur if frozen material is covered and thaws at a later time.

My gauge readings do not match my sand cone readings.

Usually they will not. There is a lot of room for operator error when performing a sand cone test. There is really no way to prove which test is more "accurate" because there is no absolute test for soil density. The best way to compare the two test methods is to take at least three 4 minute nuclear gauge measurements at different locations (preferably direct transmission @ 6 or 8 inches) and at least 3 sand cone tests (at the same locations as the gauge readings). Find the difference at all locations and average them.

Should I take a backscatter or direct transmission reading on aggregate base? (usually 4"- 6" in thickness)

Either one would be acceptable. The best thing to do is try one of each. Ideally the direct transmission will give a more representative reading, but it may also disturb the larger aggregate and lower the density. If you try both in the same spot (backscatter test first) and see which gives a better reading you can make the decision for yourself. If the material thickness is over 4", direct transmission is more appropriate in order to get a representative measurement.

What is the prescale factor for my Troxler gauge?

In order to scale the count values to a reasonable number of digits, Troxler devices use prescale factors when performing measurements, standard counts and any other diagnostics count. In other words, the count that a gauge displays is the total number of ionization events measured by the gauge divided by the appropriate prescale factor. The prescale factor is typically not needed by the gauge operator. However, the ASTM standards D 6938 and D 2950 give a formula which requires the use of the prescale factor to check the stability of the standard counts. The prescale factors are listed below: For Troxler Models 3401, 3411, 3430, 3430 Plus, 3440, 3440 Plus, and 4300 devices, a prescale of 16 is to be used in the formula when a 4-minute standard count is performed. For Troxler Models 3450 and 4640 devices, a prescale of 8 is to be used in the formula when a 4-minute standard count is performed.

Can the gauge read the moisture of a concrete slab?

It can read the moisture as a relative reading; in other words it will give an indication of a problem area, but will not give a definite moisture content. There are constituents in concrete that can cause the moisture readings to be in error, but as long as the concrete is homogeneous, the error will be constant. Example: If the slab reads approximately 12% moisture in all areas but one area is approximately 20%, it can be assumed that this is a problem area. This will give an indication of where a core sample should be taken for investigative purposes.

My 3411 gauge is giving the ERROR 30 message.

This message means that the gauge cannot calculate the test results. Usually this is due to the fact that there is no standard count in the memory. Also, this could mean that the depth switch is not correctly set; if the depth switch is set at a value much different than that which is actually being measured, the calculated results will be too large for the gauge to calculate. Try taking a new standard and checking the depth switch before taking a measurement.

Why is my gauge moisture result higher/lower than the oven dry/speedy moisture results?

The oven dry tells the true moisture content by removing all water from the sample. The gauge measures the hydrogen present in the material; which is usually in the form of water. If the material contains naturally occurring hydrogen or bound hydrogen, the gauge will measure the moisture falsely high in many cases. (Some of these materials are: mica, lime, fly ash, cement, organic materials, gypsum, coal, phosphates, etc.) A false low reading can also occur but is less common (causes include: high salt or iron oxide content or boron, lithium or cadmium present). A moisture offset will adjust for this problem.

How often do moisture/density gauges need to be calibrated?

We recommend that the gauges be properly evaluated for accuracy or calibrated every 12 months.

What are the ASTM and AASHTO standards written specifically for moisture and density testing?

ASTM C 1040 Density of Unhardened and Hardened Concrete In Place by Nuclear Methods

ASTM D 2950 Density of Bituminous Concrete In Place by Nuclear Methods

My gauge is not charging. What could it be?

For models 3440 and 4640, reset the battery life to 190 hours. Ensure charger is good. Check charger jack to see if it is loose/broken. Possible bad battery pack.

My gauge displays tube error. What's the problem?

Take the gauge to a clean, dry environment and remove the control panel or "scaler". Check for loose hardware inside the gauge that could short the high voltage. Check for moisture inside the gauge and, if moisture is present, remove the scaler and dry overnight with a fan.

Why does my gauge fail the standard count?

Ensure that the gauge is positioned properly. Make sure that those standard counts stored are appropriate by comparing to the factory standard counts reported in the most recent calibration printout. If a standard count has not been performed in more than a month and a new count fails by a small percentage (less than 5%), accept the new count and perform four more. The fifth standard count should pass.

When I try to get my density, I get nothing but +'s. Why?

Obtain the gauge's most recent calibration printout and check that the calibration constants in the memory match those on the printout. Also, verify that the depth strip is functioning correctly. Check for correct standard counts.

Why are my gauge readings off?

Ensure you have a good standard count. Verify you are at the correct depth. Check to make sure no offsets are enabled. Make sure that the handle is clicked into the notch (depth position) properly. Do not pass notch or push up on the handle after positioning it.

Why is my gauge hard to index?

Magnalube is the recommended lubricant. Place a small amount on the source rod and exercise the rod up and down. Check the bottom of the gauge to make sure dirt has not accumulated in the sliding block or base plate area.

Press and hold the OFF button for 15-30 seconds until the gauge turns off. If it does not turn off, remove the scaler and unplug the ribbon cable from the baseboard. Plug the cable back in and turn the gauge on allowing it to go through its 5 minute self-test.

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About Our Company

Since 1958, Troxler has been the worldwide leader in precision quality control and measurement equipment for the highway and construction industries. We are dedicated to providing full service, training, and maintenance support for all our products through our international sales and support offices in the US, Canada, Germany and through our 50 distributors around the world.